Increasing the field size of the Molonglo Observatory Synthesis Telescope

The Molonglo Observatory Synthesis Telescope (MOST) which at present images a fully synthesized 70 min field in 12 h, is being converted to enable observing modes which extend the field size to 160 min. The new observing modes will allow the MOST to survey completely the sky south of delta = -30 deg to a (5 sigma) sensitivity limit of about 5 mJy. The result will be a catalog of over 400,000 radio sources with a spatial density of less than 1 source per 100 beam areas, providing the foundation for a number of novel astronomical and cosmological investigations. The conversion involves construction of 352 low-noise High Electron Mobility Transistor (HEMT) preamplifiers, 88 digitally controlled UHF quad phase shifters, 88 mixers and IF sections, a new communication and control system, and several other new sub-systems. The project has been funded and developments are well advanced.